The incident was reported just before 6 a.m., when a California Highway Patrol officer saw a car stopped according to the California Highway Patrol on the Soto Street on-ramp to the westbound 10 Freeway.

A man in his 50s was found unresponsive, sitting in the driver's seat with the motor running, the Los Angeles Police Department said in a news release.

LAPD investigators believe the man was driving west on the freeway when he was shot, possibly by someone who was also driving on the highway.

The victim was shot once and died at the scene.

The motive behind the shooting is unknown.

The incident prompted the closure of the on-ramp for hours as LAPD investigated. The ramp was reopened about 10:15 a.m.

Aerial video from Sky5 showed a white tent covering the victim's car on the ramp.

Police had no information on a possible suspect or suspect and are asking anyone with information to call Hollenbeck homicide detectives at 323-342-8964.

SIGALERT UPDATE IN ALHAMBRA. SOTO ST. ON-RAMP TO WB I-10 WILL BE CLOSED FOR AN UNKNOWN DURATION DUE TO POLICE ACTIVITY